Negatively affected means if it's delayed, froze, antimattered, touched, lobotomized, etc.
It's simple stuff, really.
Things that could be contextually negative, IE SoW reflect or BE, don't count.
RT and mutate doesn't count.
Poison does.
And I'd argue it's not OP, because only the upped allows you to hurt your own creatures to get more, and your opponent can do the same to thier creatures. Their bigger, faster, stronger creatures.
Unupped, it's closer to cloak than anything else.